Question

Susan’s red notebook cover is 20 centimeters by 30 centimeters. She has a sticker for each letter in her name. Each sticker is a square that measures 3 centimeters on each side. She puts all 5 stickers on her notebook. How much of the red notebook cover is still showing?

Answer 1

Find the surface area of her notebook.

30 + 30 + 20 + 20 = 100

Now find the surface area of the square stickers.

2 + 2 + 2 + 2 = 8

So this is the surface area of one square, now multiply it by 8.

8 * 7 = 56

This is the surface area of all the stickers, now subtract it to the surface area of the notebook:

100 - 56 = 44

So 44 centimeters of the notebook cover will still be showing.

Explanation: